Himachal Pradesh University

Shimla, India

Himachal Pradesh University is a public non-profit university located in Shimla nearly 5 km away from the town of Summer Hill, in the vicinity of the Indian Institute of Advanced Study. It is wholly financed by the Government of Himachal Pradesh and the University Grants Commission, New Delhi. Wikipedia.

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Singh B.,Himachal Pradesh University
International Journal of Biological Macromolecules | Year: 2017

Present work is an attempt, to explore the potential of graphene oxide nanoplates impregnation, on the mechanical and drug delivery properties of sterculia gum-polyacrylamide composite hydrogel formed by radiation induced polymerization. These polymers were characterized by SEM, cryo-SEM, AFM, FTIR's, 13C NMR and swelling studies. Release profile of an anticancer drug ‘gemcitabine’ was studied to determine the drug release mechanism and best fit kinetic model. Furthermore, some important biomedical properties of the polymers such as blood compatibility, mucoadhesion, antioxidant properties and gel strength were also studied. Impregnation of GO into sterculia gum-poly(AAm) hydrogels decreased the swelling of hydrogels but improved the mechanical, drug loading and drug release properties of the hydrogels. Release of gemcitabine from drug loaded hydrogels occurred through non-Fickian diffusion mechanism and release profile was best fitted in first order kinetic model. These hydrogels have been found as haemocompatible, mucoadhesive, and antioxidant in nature. © 2017 Elsevier B.V.

Thakur V.K.,Washington State University | Thakur M.K.,Himachal Pradesh University
Journal of Cleaner Production | Year: 2014

Natural polysaccharide based hydrogels display unique properties such as biodegradability, biocompatibility, stimuli-responsive characteristics and biological functions making them a materials of choice for diverse applications. Indeed during the last few years, a number of biorenewable polymers based hydrogels have attracted great interest for miscellaneous applications including biomedical, toxic ion removal and water purification. Keeping in mind the advantages of biorenewable polymers, this article summarizes for the first time, the recent development in psyllium polysaccharide based hydrogels. Different methods for preparation of polysaccharide hydrogels along with characterization, their swelling behavior and different mechanisms of solvent diffusion are critically reviewed. This article also comprehensively discusses the structure-property relationships of polysaccharide hydrogels and highlights the application potential for prime performance of the resulting hydrogels. Effect of different reaction conditions and monomers on different properties of the resulting hydrogels have been explored. The most important properties of polysaccharide hydrogels relevant to their biomedical/environmental applications are also identified, especially for the use of polysaccharide hydrogels as drug delivery/flocculant and superabsorbent systems. It is anticipated that the interest in natural polysaccharide based hydrogel will continue to grow as value - added green materials for multifunctional applications.

Thakur V.K.,Washington State University | Thakur M.K.,Himachal Pradesh University
Carbohydrate Polymers | Year: 2014

Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental friendliness, flexibility, easy processing and impressive physico-mechanical properties. Natural cellulose fibers based materials are finding their applications in a number of fields ranging from automotive to biomedical. Natural cellulose fibers have been frequently used as the reinforcement component in polymers to add the specific properties in the final product. A variety of cellulose fibers based polymer composite materials have been developed using various synthetic strategies. Seeing the immense advantages of cellulose fibers, in this article we discuss the processing of biorenewable natural cellulose fibers; chemical functionalization of cellulose fibers; synthesis of polymer resins; different strategies to prepare cellulose based green polymer composites, and diverse applications of natural cellulose fibers/polymer composite materials. The article provides an in depth analysis and comprehensive knowledge to the beginners in the field of natural cellulose fibers/polymer composites. The prime aim of this review article is to demonstrate the recent development and emerging applications of natural cellulose fibers and their polymer materials. © 2014 Elsevier Ltd. All rights reserved.

Thakur V.K.,Washington State University | Thakur M.K.,Himachal Pradesh University
International Journal of Biological Macromolecules | Year: 2015

Recently, biorenewable polymers from different natural resources have attracted a greater attention of the research community for different applications starting from biomedical to automotive. Lignin is the second most abundant non-food biomass next to cellulose in the category of biorenewable polymers and is abundantly available as byproduct of several industries involved in paper making, ethanol production, etc. The development of various green materials from lignin, which is most often considered as waste, is therefore of prime interest from environmental and economic points of view. Over the last few years, little studies have been made into the use of lignin as an indispensable component in the hydrogels. This article provides an overview of the research work carried out in the last few years on lignin based hydrogels. This article comprehensively reviews the potential efficacy of lignin in biopolymer based green hydrogels with particular emphasis on synthesis, characterization and applications. In this article, several examples of hydrogels synthesized using different types of lignin are discussed to illustrate the state of the art in the use of lignin. © 2014 Elsevier B.V.

Kumar A.,Himachal Pradesh University | Ahluwalia P.K.,Himachal Pradesh University
Journal of Alloys and Compounds | Year: 2013

We have performed first principle pseudopotential and numerical pseudoatomic orbitals basis set based calculations to study the influence of slab thickness on the electronic and dielectric properties of niobium dichalcogenides (S, Se, Te). We have taken bulk, mono, bi, quadri and six-layer setup for this study. The importance of semicore states in Nb pseudopotential has been investigated. Electronic band structures of studied materials show splitting of the bands of the order of 0.7 eV at Γ point due to interlayer interactions for all the materials under consideration. Electron energy loss spectra (EELS) for in-plane polarization shows 0.65 eV (6.5 eV), 0.75 eV (7.5 eV) and 0.55 eV (6.9 eV) red shift in energy of π(π + σ) plasmons peaks respectively for NbS2, NbSe2 and NbTe2 by reducing the slab thickness from bulk to monolayer, while for out-of-plane polarization, approximately ≈6.3 eV red shift in π + σ plasmons peak has been found for all the studied materials on reducing the number of layers from bulk to monolayer. Interband transitions energies are found to remain same irrespective of the quantum confinement effect for all the dichalcogenides of Nb with an additional interband transition at 3.2 eV for NbTe2. © 2012 Elsevier B.V. All rights reserved.

Kumari S.,Himachal Pradesh University | Chauhan G.S.,Himachal Pradesh University
ACS Applied Materials and Interfaces | Year: 2014

Mercury is a highly toxic environmental pollutant; thus, there is an urgent need to develop new materials for its simultaneous detection and removal from water. In the present study, new oxidized cellulose-based materials, including their Schiff bases, were synthesized and investigated as a sensor-adsorbent for simple, rapid, highly selective, and simultaneous detection and removal of mercury [Hg(II)] ions. Cellulose was extracted from the pine needles, etherified, oxidized, and modified to Schiff base by reaction with l-lysine. The well-characterized cellulose Schiff base materials were used as a sensor-adsorbent for Hg(II) from aqueous solution. Hg(II) sensing was analysed with naked-eye detection and fluorescence spectroscopy. Schiff base having a decyl chain, C10-O-cell-HC=N-Lys, was observed to be an efficient adsorbent with a very high maximum adsorption capacity of 258.75 mg g -1. The data were analyzed on the basis of various kinetic and isotherm models, and pseudo-second-order kinetics and Langmuir isotherm were followed for Hg(II) adsorption. © 2014 American Chemical Society.

Kumar A.,Himachal Pradesh University | Kanwar S.S.,Himachal Pradesh University
Bioresource Technology | Year: 2011

In the present work we have evaluated synthesis of ethyl ferulate by the esterification reaction of ferulic acid and ethanol catalyzed by a commercial lipase (Steapsin) immobilized onto celite-545 in a short period of 6h in DMSO. The immobilized lipase was treated with cross-linking agent glutaraldehyde (1%; v/v). The optimum synthesis of ethyl ferulate was recorded at 45°C, pH8.5 and 1:1 ratio of ethanol and ferulic acid. Co2+, Ba2+and Pb2+ ions enhanced the synthesis of ethyl ferulate Hg2+, Cd3+and NH4+ ions had mild inhibitory effect. The celite-bound lipase produced 68mM of ethyl ferulate under optimized reaction conditions. © 2010 Elsevier Ltd.

Kumara A.,Himachal Pradesh University | Ahluwalia P.K.,Himachal Pradesh University
European Physical Journal B | Year: 2012

We report first principles calculations of the electronic structure of monolayer 1H-MX2 (M = Mo, W; X = S, Se, Te), using the pseudopotential and numerical atomic orbital basis sets based methods within the local density approximation. Electronic band structure and density of states calculations found that the states around the Fermi energy are mainly due to metal d states. From partial density of states we find a strong hybridisation between metal d and chalcogen p states below the Fermi energy. All studied compounds in this work have emerged as new direct band gap semiconductors. The electronic band gap is found to decrease as one goes from sulphides to the tellurides of both Mo and W. Reducing the slab thickness systematically from bulk to monolayers causes a blue shift in the band gap energies, resulting in tunability of the electronic band gap. The magnitudes of the blue shift in the band gap energies are found to be 1.14 eV, 1.16 eV, 0.78 eV, 0.64, 0.57 eV and 0.37 eV for MoS2, WS2, MoSe2, WSe2, MoTe2 and WTe2, respectively, as we go from bulk phase (indirect band gap) to monolayer limit (direct band gap). This tunability in the electronic band gap and transitions from indirect to direct band make these materials potential candidates for the fabrication of optoelectronic devices. © EDP Sciences, Societá Italiana di Fisica, Springer-Verlag 2012.

Prakash J.,Himachal Pradesh University
Journal of Magnetism and Magnetic Materials | Year: 2012

It is shown analytically that the 'principle of the exchange of stabilities' (PES), in general, is not valid in ferromagnetic convection in a ferrofluid layer, for the case of free boundaries and hence a sufficient condition is derived for the validity of the PES. Upper bounds for the complex growth rate are then obtained. It is proved that the complex growth rate σ= σri σi (where σ r and σ i are, respectively, the real and imaginary parts of σ) of an arbitrary oscillatory motion of growing amplitude, in ferromagnetic convection in a ferrofluid layer, for the case of free boundaries lies inside a semicircle in the right half of the σ rσ i-plane whose center is at the origin and ( radius)2=R M1/ Pr, where R is the Rayleigh number, M1 is the magnetic number and Pr is the Prandtl number. Further, bounds for the case of rigid ferromagnetic boundaries are also derived separately. © 2011 Elsevier B.V. All rights reserved.

Specific conductance of (0.3 to 3.0) mmol · kg-1 sodium dodecyl benzene sulfonate (SDBS) and (3.0 to 30.0) mmol · kg-1 dodecyltrimethylammonium bromide (DTAB) has been determined in water and in the presence of (0.01, 0.05 and 0.10) mol · kg-1 aqueous solution of glutamine/histidine/methionine at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K. From the conductivity data, the critical micellar concentration (CMC) and thermodynamic parameters of micellization (ΔGmo,ΔHmo and ΔSmo) have been computed by applying the mass action model. Enthalpy-entropy compensation effect has also been observed. The effect of amino acid on the micellar properties of SDBS and DTAB depends upon their nature, concentration, as well as on temperature and has been used to study the interactions present in the micellar systems. There occurs a gradual increase in the value of CMC with temperature in case of SDBS while in case of DTAB, it passes through a broad minimum and then tends to increase with increase in temperature. Increase of amino acid concentration is found to decrease CMC in both the surfactants. The ΔGmo values are negative and the feasibility of the micellization is found to increase with rise in temperature. The magnitude of hydrophilic and hydrophobic dehydration determines whether the CMC values increase or decrease with rise in temperature. © 2013 Elsevier Ltd. All rights reserved.

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